Electrostatic transformer



June 9, 1931. J. F. PETERS ELECTROSTATIC TRANSFORMERS Filed Oct. 16,

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ATTORNEY Patented June 9,1931

UNITED STATES PATENT OFFIC JOIEDT F. PETERS, OI PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8: MANUFACTURING COMPANY, A CORPORATION OF BENNSYLVANIA mno'mosmrrc TRANSFORMER Application filed October 16,1925. Serial No. 62,737.

' My invention relates to transformers and particularly to electrostatic transformers.

One object of my invention is to provide an electrostatic means for deriving a reduced voltage from an. electric transmission line to energize measuring instruments.

Another object of my invention isto provide means for deriving a reduced voltage from an electric transmission line without o ,entailinga substantial loss of electric power;

Another object of my invention is to provide means for deriving a reduced voltage by electrostatic induction.

A further ob'ect of my invention is to provide means or deriving a reduced voltage from an electric transmission line that shall be inexpensive to manufacture, accurate in operation and of such simple, sturdy construction that it requires but little attention.

In the prior art, both electromagnetic transformers and resistors have been used to derive a reduced voltage from a transmission line but these methods dissipate 26 current and are, therefore, objectionable.

In my co-pending application Serial No. 680,569, filed December 13, 1923, surge recorders, and assi nod to the Westinghouse Electric & Manu acturing Company, I have 30 described an instrument for obtaining a record of the nature of a surge occurring in a high voltage system. The instrument comprises two conducting elements disposed on opposite sides of a sensitized film to sub- .ject the film to a potential difference derived from the system and proportional to the voltage developed by the surge,

Inasmuch as the sensitized film or plate will be influenced only by the impression of potential diiferences in excess of a predetermined value, it is desirable to provlde some means for readily obtaining a potential difference that shall be a function of the system voltage or of the voltage developed in the system by a surge in order that the sensitized film or plate may be subjected to such derived voltage.

The derived voltage is normally less than the critical value at which the plate or film 59 will respond so that under normal conditions no indication is effected on the film or plate. Under abnormal conditions, however, the voltages are sufiiciently increased so that the derived voltage is also increased above the critical value at which the film or plate responds to the impressed potential difi'er ence.

In order to derive a reduced potential difference which shall be a function of the line voltage in a simple and economical manner, I provide in accordance with my invention, an electrostatic transformer com.- prising two metal plates, one at line potential and one at zero potential, separated by an air-space. A third metal plate is interposed in the air-space and is charged by the electrostatic field to a potential inversely proportional to the distance separatin this plate from the top plate. The potential of this middle plate is used to operate an electric measuring instrument of the type shown in my copending application.

Figure 1 of the accompanying drawings is a front elevational View of an electrostatic transformer embodying my invention.

F1g.'2 is a top view of the transformer shown in Fig. 1.

The electrostatic transformer of my invention comprises,,in general, a static shield 1, a ground plate 2, a condenser plate or ring 3 and a switch 4.

The static shield 1 is a horizontally disposed ringsupported by a vertically disposed pillar insulator 5 and is charged to the potentialof the line through a conductor 6 leading from the line 7. The shield is constructed of iron pipe of such size and diam eter that no corona is formed when it is charged to any potential the line may carry.

The insulator pillar 5 is vertically disposed and consists of porcelain members connected by metal pins and is sutliciently hi gh to reclude arcs jumping the air-space separating the static shield 1 from the ground plate 2. A cross member 8 is attached to the top of the'insulator pillar which is bolted to the static shield 1 and carries its weight.

The ground plate 2 is a horizontally disposed metal plate at the base of the insulator pillar 5 and is substantially larger, in horizontal dimensions, than the :static shield 1. As the name implies, the ground plate 2 rests directly on the ground or is connected to it.

The condenser plate 3 is a ring similar to the static shield 1, horizontally disposed in the air-space separating the static shield 1 and the ground plate 2 and is so placed that. it conforms with the vertically downward projected outlines of the static shield- 1. Two insulators 9 and 10 are diametrically attached to the ring3 and adjustably sup port it in .a position sufliciently near the static shield 1 to give the voltage desired for the manipulation of indicating instruments. The insulator pillar 5 projects through the a center of the conde'nser plate or ring 3, but

the air space intervening is sufliciently wide to prevent arcing between the said members.

The switch 4 is a controlling switch placed in a circuit between'the condenser'plate or ring 3 and the indicating instrument 11, that is located within a shelter 12, and provides a means for short-circuiting the condenser plate 3 with the ground when it is desired to andle the indicating instrument 11.

In operation, the line 7 is charged to a high potential which is communicated by the conductor 6 to the static shield 1. An electrostatic field is set up between the static shield. 1 and the ground plate 2, which includes the condenser plate 3, inducing an electrostatic potential therein, which, when the switch 4 is open, is transmitted through a circuit comprising the conductor 13 to an indicating instrument 11 disposed in the shelter 12. I

When the switch 4 is closed, it connects the ring 3 directly to the ground plate and precludes any danger to one handling the instrument 11'.

said ground plate for su'porting' said ele-- ment in operative relation with said ground plate.

respect to 2. An electrostatic transformertor deriving a reduced potential from a high-potential circuit comprising a ground-plate, a second plate cooperating therewith to constitute a high capacity condenser, a column of high potential insulators supported upon said ground plate and engaging'said second plate to support the same in operative position, a third plate, and means for adjustably supporting said third plate between said ground plate'and second plate.

3. A high capacity condenser comprising two spaced elements constituting "condenser plates, and means for maintaining said elements in spaced relation comprising a column of high potential pin-type insulators extending therebetween and secured thereto.

4. 'An electrostatic transformer for deriving a reduced potential from a high-potene tial circuit including a ground plate, a conducting element spaced therefrom in condensive relation therewith and electrically connected to said circuit, said element being approximately parallel to said ground plate,

and means comprising a plurality of superposed high-potential insulators supported upon said ground plate for supporting said element in operative relation with respect to said ground plate, said insulators being positioned one above the other in a direction perpendicular to the plane of said ground plate.

In testimony whereof, I have hereunto subscribed my name this 8th day of October,

JOHN F. PETERS.

My invention provides a means for supplying a safe potential for potential indicating instruments. The values indicated b the associated instruments, after proper a justments, bear a constant relation to the corresponding values of the transmission line, which may easily be ascertained by multiplying the values observedby a predetermined constant, or instruments may be calibrated to give line values directly. The 

